The present invention relates to wireless systems, and more particularly, to methods and systems for a modular wireless system.
FIG. 1 illustrates a block diagram of a current cellular system 100. As illustrated, the system includes a mobile switching center (MSC) 120 connected to multiple base station controllers (BSC) 130. The MSC 120 is also connected to other networks 160, a home location register (HLR) 140, and visitor location register (VLR) 150. Further, each BSC is connected to one or more base transceiver systems (BTS) 110. The MSC 120 is typically an automatic system that interfaces the user traffic from a wireless network to a wireline network or other wireless networks. The MSC 120 is also often called the mobile telephone switching office (MTSO) or the personal communications switching center (PSC).
The BTS 110 typically consists of one or more transceivers placed at a single location and terminates the radio path with wireless devices. The BTS 110 may be co-located with a BSC 130 or may be independently located. The BSC 130 is the control and management system for one or more BTSs 110. The BSC 130 exchanges messages with both the BTS 110 and the MSC 120.
The HLR 140 is the functional unit used for management of wireless subscribers by maintaining all subscriber information (e.g., electronic serial number, directory number, international mobile subscriber identity, user profiles, current location, etc.). The HLR 140 may be co-located with a MSC 120, be an integral part of the MSC 120, or may be independent of the MSC 120. One HLR 140 can serve multiple MSCs 120, or an HLR 140 may be distributed over multiple locations.
The VLR 150, which is linked to one or more MSCs 120, dynamically stores subscriber information (e.g., ESN subscriber's, directory number, user profile, etc.) obtained from the wireless subscriber's HLR 140 when the wireless device is located in the area covered by the VLR 150. When a roaming wireless device enters a new service area covered by a MSC 120, the MSC 120 informs the associated VLR 150 about the wireless device by querying the HLR 140 after the wireless device goes through a registration procedure.
The other networks 160 may include other communications networks, such as a public switched telephone network (PSTN), an Integrated Services Digital Network (ISDN), a Public Land Mobile Network (PLMN), and a packet-switched public data network (PSPDN).
In the current cellular system 100, the BTSs 110, BSCs 130 and MSC 120 are hardwired together. That is, they have direct physical connections between each other. As a result, the costs necessary for building such an infrastructure can be prohibitively large, making it difficult, if not impossible, for companies to enter the cellular marketplace.